1. Field of the Invention
The present invention relates to a composite sheet material. More particularly, the present invention relates to a stainproof composite sheet material having enhanced heat resistance, weathering resistance, and waterproofness.
2. Description of the Related Art
Sheet materials containing a synthetic resin coating layer are used in various industrial fields, for example, housing, civil construction, interior decoration, automobiles, aircraft, and boats. However, conventional synthetic resins for coating the sheet materials, for example, polyvinyl chloride, are disadvantageous in that when the resins are heated at a high temperature, they burn and give off large amounts of harmful or toxic gas and smoke are generated. Various attempts have been made to make the conventional resins noncombustible or fire retardant. For example, Japanese Examined Patent Publication (Kokoku) No. 55-4582 discloses a fire-retardant sheet material comprising a fibrous substrate and a coating layer consisting of a polyvinyl chloride resin mixed with a mixture of a borate, a zinc compound, or iron compound with aluminum hydroxide or barium sulfate. However, the resultant fire-retardant property of the sheet material is not always satisfactory.
In another example, Japanese Examined Patent Publication (Kokoku) Nos. 53-13505 and 51-37397 and Japanese Unexamined Patent Publication (Kokai) No. 54-68470 disclose attempts to use silicone resins or rubbers as a fire-retardant resin. In these attempts, the resultant fire-retardant property of the sheet material is considerably high. However, utilization of silicone resins or rubbers has the disadvantage that the coating layer, which is soft and delicate, is easily stained by oily dusts or solid dusts or sometimes peels when the sheet material is used in the open air.
Accordingly, it is important to eliminate the above-mentioned disadvantage from silicone resin or rubber-coated sheet materials.